Power supply usage determination

ABSTRACT

The remaining capacity of a power source, such as a battery, may be monitored with a microprocessor by integrating data received from a current sensor. The microprocessor may measure electrons passing through the battery by sampling the integrator and summing the values recorded from the integrator. Each time the integrator is sampled, the microprocessor may reset the integrator to prevent the integrator from saturating. The microprocessor may sample the integrator when the integrator approaches a predetermined value. The remaining capacity of the battery may be calculated based on calibration values and the sum of electrons measured by the integrator. The remaining capacity may be communicated to remote users through a network and displayed in an executive dashboard.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/525,549 to Claude Leonard Beckenstein, Jr. et al., filed on Jun. 18,2012, and entitled “Power Supply Usage Determination,” which is acontinuation of U.S. patent application Ser. No. 13/036,435 to ClaudeLeonard Beckenstein, Jr. et al., filed on Feb. 28, 2011, and entitled“Method for Determining Power Supply Usage,” which is a continuation ofU.S. Pat. No. 7,917,315 to Claude Leonard Benckenstein, Jr. et al.,filed on Aug. 13, 2008, and entitled “Method for Determining PowerSupply Usage,” each of which are hereby incorporated by reference.

TECHNICAL FIELD

The present embodiments relate to a method for measuring electron flowto determine remaining capacity of a power supply, such as a lithiumprimary battery, a lithium ion battery, a lead-acid battery, a fuelcell, a solar panel system, or other power supply.

BACKGROUND

A need exists for a method that accurately measures and tracks electronflow that is portably usable in many environments, easy to undertake,and inexpensive to operate.

A further need exists for a method that can be installed on a widevariety of power supplies for remote and close proximity monitoring ofelectron usage by a customer, a user, and an administratorsimultaneously, that does not require measurement of time to determineremaining capacity.

The present embodiments meet these needs.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description will be better understood in conjunction withthe accompanying drawings as follows.

FIG. 1 is a depiction of an amplitude signal for use herein according toone embodiment of the disclosure.

FIG. 2 is a flow chart of the method according to one embodiment of thedisclosure.

FIG. 3 is a diagram of a fuel gauge usable in the method according toone embodiment of the disclosure.

DETAILED DESCRIPTION

Before explaining the present embodiments in detail, it is to beunderstood that the invention is not limited to the particularembodiments and that it can be practiced or carried out in various ways.

The present embodiments relate to a method for tracking electron flowfrom a power supply using a networked system. The system can utilizealarms and/or meters when electron flow is at a reduced level byaccurately and with high precision tracking the electron flow.

Typically, remaining capacity of a power source is measured by recordingthe amount of current maintained per a unit of time. In extremeconditions, such as the high temperatures and pressures encounteredwithin a wellbore, the accurate tracking of the passage of time, such asthrough use of a processor-based clock, is not possible.

The present method enables measurement of the capacity of a power sourceindependent of elapsed time by tracking electron flow, rather thancurrent per unit time. During operation of a power source, current ismeasured and converted to a voltage proportional to the current. Thevoltage proportional to current is converted and recorded as a monotonicuni-polar representation of an aggregate number of electrons. Subsequentrepresentations are accumulated until this value reaches a calibrationconstant, at which time a known quantity of current has been maintained,such as one mA/hour, enabling capacity of the power source to becalculated in standard engineering units. The accumulated value can thenbe reset, allowing further accumulation until the calibration constantis again reached.

The method relates to counting electrons from a power supply.

First, a current from a power source is measured which is then termed “ameasured current.”

The power supply can be a lithium primary battery, a lithium-ionbattery, a lead acid battery, a fuel cell, or another source ofelectrical energy that provides a flow of electrons in a direct current,such as electrons generated by an alternator of a car, or a generator ofa boat or RV.

Next, the measured current is converted to a voltage. The conversionoccurs, in an embodiment, using a current sense resistor, such as amodel WSL2512RI000FEA resistor made by Vishay of the state ofPennsylvania. The current sense resistor can handle between about 0 ampsand about 6 amps. This current sense resistor is placed in series withthe load, the load being the device powered by the power supply. In thisconfiguration the current at the current sense resistor is the same atthe current drawn off the power supply.

The current can be a pulsed current or a constant current. In anembodiment, if the current is pulsed, is can be pulsed at about 2 ampsevery one second or about 1 amp every 2 seconds, or other variations ofpulsed current. If the current is constant, for example, it can be about100 mA.

The converted current is integrated into a monotonic uni-polarrepresentation of an aggregate number of electrons through a Deboointegrator. The amplitude of the voltage is representative of theaggregate number of electrons flowing through a current sense resistorafter integration using a Deboo (non-inverting) integrator with acapacitor.

The Deboo integrator is a non-inverting uni-polar integrator that formsa monotonic, unidirectional signal, wherein the amplitude represents thenumber of electrons flowed, similar to a trip odometer tracking mileageof a car. Other integrators can be usable herein, such as passiveintegrators generally known in the field of electrical engineering.

When the integrator output voltage reaches a preset limit, or athreshold, then the monotonic uni-polar representation of the aggregatenumber of electrons is “read” by the microprocessor forming a readinginternal to the microprocessor. This reading is representative of thefact the preset limit has been reached and a corresponding number ofelectrons have passed through the current sense resistor.

Using an analog-to-digital converter, such as a AD7819 made by AnalogDevices, the monotonic uni-polar representation of the number ofaggregate electrons is identified and stored in memory of themicroprocessor. Additionally, in an embodiment it is contemplated thatthe reading is formed using an analog to digital converter within themicroprocessor.

Prior to electron saturation, the reading can be made by themicroprocessor, which can be a model MC908QBMDTE, made by Freescale ofAustin, Tex. The microprocessor has a processor and data storagecontaining computer instructions for instructing the processor toaccumulate the amplitude each time the output of the integrated reachesa preset limit. Each reading is added to a memory location in the datastorage where it is combined with previous readings forming a summation.

The microprocessor contains instructions for storing the value of theamplitude voltage and for adding each value to a previous sum forming arunning summation. The summation, being representative of the number oftimes the output of the integrator has reached the preset limit, whichis also proportional to the total charge which has passed from the powersource.

Additionally, the microprocessor contains instructions for resetting theintegrator, or discharging the integrator, once the voltage of theamplitude signal reaches a preset limit. Once this occurs, the amplitudesignal will be reset, and will generally increase as a function of thesignal input into the integrate as previously described.

The readings are repeated by actuating of the microprocessor before theintegrator reaches the preset limit. With each reading, the accumulatorvalue is transmitted to the accumulator, and the summation continues,causing the accumulator value to increase or remain constant, but neverdecrease.

The summation is then compared to a calibration value stored on themicroprocessor for the particular fuel gauge. The calibration value ispreloaded in the data storage. The calibration value is unique to eachdesignated fuel gauge circuit. An example of a calibration value is14,000. It should be noted that when the accumulator reaches thecalibration constant, a known quantity of power has flowed, such as 1mAH, enabling accurate electron tracking and determination of powersource capacity.

The comparison can then be recorded as an established standardengineering unit of capacity, such as Amp Hours, when the summation ofaccumulator values meets or exceeds the calibration value.

In an additional embodiment, the fuel gauge can monitor and recordambient temperature, that is the temperature surrounding the powersupply using a temperature sensor. After the temperature is read, thenthe established standard engineering unit of capacity is adjusted basedon the ambient temperature.

In the fuel gauge, the current sense resistor is a sensor thatdetermines current proportional to voltage. An example of such a currentsense resistor is model WSL2512RI000FEA made by Vishay of Pennsylvania.

The microprocessor used in the method enables the sensing of electronflow at temperatures ranging from about −40 degrees Centigrade to about150 degrees Centigrade.

It should be noted that the established standard engineering unit ofcapacity, from the microprocessor, can be determined using a reader in amanner known to those in the field of electrical engineering.

In one embodiment, the fuel gauge can have a reader that communicatesthe established standard engineering unit of capacity to a user who isusing at least one light emitting diode.

The communication from the reader can be over a wireless network, a hardwired network, a satellite network, or combinations thereof. The usercan be connected to a website, or be connected to a graphical userinterface display directly for viewing electron flow, and the fuel usageoccurring to the power supply.

When the reader is in communication with a network, the fuel gaugepermits continuous and automatic remote monitoring of power supplycapacity.

An example of automatic, and continuous, real time monitoring is with anexecutive dashboard that is continually pushing the data to the user,rather than the user asking for the data. This push enables better andmore accurate monitoring of the fuel use.

Monitoring using an executive dashboard enables a user to view thatconstant status of multiple power supplies, such as batteries, eachconnected via the network for constant and highly accurate measurement,such within 1 mV. Monitoring using an executive dashboard also allowsfor less waste of fuel, particularly in a remote environment, such as arecharging station for military radios in the middle of a barren arcticwasteland.

In an embodiment it is contemplated that the capacitor of the integratorhas at least two miniature 0.01 microfarad value capacitors, each havinga low loss, high temperature rating, such as 125 Centigrade, with amoderately high capacitance.

It is contemplated that a moderately high capacitance would beequivalent to about 0.22 microfarads for each capacitor.

The two capacitors can be contemplated to be connected in parallel andtherefore provide a capacitance of about 0.44 microfarads. An example ofsuch a miniature 0.01 microfarad value capacitor would be a high techplastic fill capacitor made by Fujitsu.

A different embodiment contemplates that the capacitor can be aprecision capacitor, which would have a capacity of about 0.02microfarads.

In an embodiment the preset limit of aggregate electrons can be no morethan three volts using a 12 bit converter.

Turning now to the figures, FIG. 1 illustrates a representativeamplitude signal produced by the integrator for use in the inventionherein. The voltage (60) produced by the integrator is a function of thevoltage of the current sense resistor. The signal produced in FIG. 1represents a generally linear increase in the voltage output by theintegrator as a result of a generally constant input voltage. FIG. 1also illustrates the saturation point V₁ (62) of the integrator. It canbe seen once the integrator becomes saturated, the output voltage nolonger increases regardless of the input voltage. FIG. 1 illustrates apreset limit (64) at V₂, which is selected at a voltage below thesaturation point V₁ (62) of the integrator. In the operation of thedevice a reading will be taken when the preset limit (64) is reached andthe integrator will be discharged. The amplitude signal can vary basedupon the input signal in a predictable way known to those in the artbased on the configuration of the integrator.

FIG. 2 shows a method for counting electrons from a power supply, themethod comprising the following steps: measuring a current of a powersupply forming a measured current (100); converting the measured currentto a voltage (102); integrating the voltage into a monotonic uni-polarrepresentation of an aggregate number of electrons having an amplituderepresentative of the aggregate number of electrons flowing through acurrent sense resistor using an integrator having a capacitor (104);actuating a microprocessor in communication with a data storage justbefore the integrator reaches a preset limit of aggregate electrons(106); reading the amplitude representative of the aggregate number ofelectrons from the integrator with the microprocessor forming a reading(108); transmitting the reading to an accumulator formed in the datastorage forming an accumulator value (110); resetting the integratorafter transmitting the reading (112); repeating the actuation of themicroprocessor before the integrator reaches the preset limit, makingadditional readings and repeating the transmission to the accumulatorand repeating the formation of a summation of accumulator values usingthe additional readings (114); compare the summation of accumulatorvalues to a calibration value; wherein the calibration value is uniqueto a designated fuel gauge circuit and when the summation of accumulatorvalues reaches the calibration value, 1 mA/hour has flowed (116) andrecording an established standard engineering unit of capacity when thesummation of accumulator values meets or exceeds the calibration value(118). A second accumulator can be used to record quantities of batteryusage.

FIG. 3 shows the fuel gauge usable in this method. The fuel gauge has,in an embodiment, a voltage pre-regulator (10) for receiving current andproviding a preset voltage. The voltage pre-regulator (10) is designedfor 10-80V applications to provide 6 Volts. In an embodiment, thevoltage pre-regulator can be resistant to extreme temperature, highpressure, shock and vibration.

Additionally, the fuel gauge has a main voltage regulator (12) incommunication with the voltage pre-regulator for receiving the presetvoltage and providing power to other components of the fuel gauge. Theregulator can be a band gap device, designed for precision measurementapplications, and is contemplated to be precise to within about 1percent. In an embodiment, the main voltage regulator can have a maximumvoltage tolerance of about 80V. In one embodiment the main voltageregulator can contain a temperature sensor (48).

An example of the voltage pre-regulator would be one such as LT3014BES5made by Micropower. An example of the main voltage regulator would beone such as those produced by Analog Devices.

A current sense resistor (14), such as a model WSL2512RI000FEA resistormade by Vishay, is in communication with the main voltage regulator forconverting the current to a voltage proportional to the current.

In an embodiment, the main voltage regulator can be a precisionregulator, and the current sense resistor can be a precision resistor.

An integrator (16) is shown, comprising an op amp (18) such as aLTC2054HS5 made by Linear Technologies and a capacitor (20). Theintegrator (16) receives power (22) from the main voltage regulator, andan input voltage proportional to current (24) from the current senseresistor. In an embodiment, the integrator can have a saturation voltageranging from about 0 volts to about 3 volts.

A microprocessor (26) with data storage (28), such as a MCQB8DTE made byFreescale, can be used in combination with a hysteresis circuit (30).Those of ordinary skill in the art can appreciate that the hysteresiscircuit can be either be an external component for conditioning theamplitude signal of the integrator, or the hysteresis circuit can becontained within the microprocessor. The microprocessor is contemplatedto remain in a low power state until activated. In one embodiment, themicroprocessor can consume from one to three microwatts of power in thelow power state.

The data storage, which can be fixed, removable, or remote data storage,can include computer instructions (32) for instructing themicroprocessor to convert the voltage across the current sense resistorto a monotonic uni-polar representation of an 15 aggregate number ofelectrons (34).

A resistor (36) is disposed between the integrator and themicroprocessor for activating the microprocessor from the low powerstate prior to saturation of the integrator with the voltageproportional to current.

A reset circuit (38) is disposed between the microprocessor and theintegrator for resetting the monotonic uni-polar representation of anaggregate number of electrons to zero. In an embodiment, the resetcircuit resets the integrator to zero in less than three microsecondsfor ensuring accuracy.

In an embodiment, the fuel gauge has a modem (40) for providing acommunication signal (42) over power lines of the fuel gauge. A switch(44) can be used for controlling power to the modem.

In an embodiment, the op amp can be a low power and low drift device.The op amp can be one such as model LTC2054HS5 from Linear Technologywhich provides a low pollution due to noise. The op amp can receivepower from the main voltage regulator. The op amp operates using a logicinput that cycles to activate and deactivate the op amp.

The hysteresis circuit provides a discrete rapid output in response to aslowly changing input. The output of this circuit can be either logic 0or 1, but input must change significantly for output to change.

While these embodiments have been described with emphasis on theembodiments, it should be understood that within the scope of theappended claims, the embodiments might be practiced other than asspecifically described herein.

What is claimed is:
 1. An apparatus, comprising: a current sensorcoupled to an output of a power source; an integrator coupled to thecurrent sensor; a memory configured to store an electron count value anda calibration value; a voltage regulator coupled to the current sensorand to the power source; and a microprocessor coupled to the currentsensor, to the integrator, and to the memory, in which themicroprocessor is configured to: obtain an electron count from theintegrator; increment the electron count value stored in the memory bythe electron count obtained from the integrator; read a calibrationvalue from the memory; and calculate a power usage of the power sourcebased, at least in part, on the electron count value and the calibrationvalue.
 2. The apparatus of claim 1, further comprising a hysteresiscircuit coupled to the microprocessor in which the hysteresis circuit isconfigured to condition an amplitude of a signal received from theintegrator.
 3. The apparatus of claim 2, in which the hysteresis circuitis integrated with the microprocessor.
 4. The apparatus of claim 1,further comprising an analog-to-digital converter coupled to theintegrator and to the microprocessor, in which the microprocessor isfurther configured to obtain the electron count from the integrator as adigital value from the analog-to-digital converter.
 5. The apparatus ofclaim 4, in which the analog-to-digital converter is integrated with themicroprocessor.
 6. The apparatus of claim 1, further comprising a modemcoupled to the microprocessor, in which the microprocessor is configuredto communicate at least one of the electron count value and the powerusage through the modem.
 7. The apparatus of claim 1, in which thecalibration value is specific to the apparatus.
 8. The apparatus ofclaim 1, further comprising a temperature sensor coupled to themicroprocessor, in which the microprocessor is configured to: measure anambient temperature from the temperature sensor; and adjust thecalibration value based, at least in part, on the measured ambienttemperature.
 9. The apparatus of claim 1, in which the voltage regulatorcomprises a band gap device configured to provide power to theapparatus.
 10. The apparatus of claim 1, further comprising a voltagepre-regulator coupled to the voltage regulator.
 11. The apparatus ofclaim 10, in which the voltage pre-regulator is configured to receive acurrent and provide a preset voltage.
 12. A method, comprising:regulating, by a voltage regulator, a voltage for powering a fuel gauge;obtaining, by a microprocessor of the fuel gauge, an electron count froman integrator coupled to a power source; incrementing, by themicroprocessor, an electron count value in a memory by the obtainedelectron count; reading, by the microprocessor from the memory, acalibration value; and calculating, by the microprocessor, a power usageof the power source based, at least in part, on the electron count valueand the calibration value stored in the memory.
 13. The method of claim12, further comprising resetting, by the microprocessor, the integratorwhen the electron count is obtained from the integrator.
 14. The methodof claim 12, further comprising converting the power usage of the powersource into an established unit of capacity based, at least in part, onthe calibration value.
 15. The method of claim 12, further comprising:measuring an ambient temperature of the power source; and adjusting thecalibration value based, at least in part, on the measured ambienttemperature.
 16. The method of claim 12, further comprising reporting,by the microprocessor to a remote monitor through a modem, at least oneof the electron count value and the power usage of the battery.
 17. Themethod of claim 12, in which obtaining the electron count comprisesreceiving an analog signal from the integrator, the method furthercomprising conditioning the analog signal received from the integrator.18. An apparatus, comprising: a current sensor coupled to an output of apower source; an integrator coupled to the current sensor; a memoryconfigured to store an electron count value and a calibration value; ahysteresis circuit coupled to the microprocessor in which the hysteresiscircuit is configured to condition an amplitude of a signal receivedfrom the integrator; and a microprocessor coupled to the current sensor,to the integrator, and to the memory, in which the microprocessor isconfigured to: obtain an electron count from the integrator; incrementthe electron count value stored in the memory by the electron countobtained from the integrator; read a calibration value from the memory;and calculate a power usage of the power source based, at least in part,on the electron count value and the calibration value.
 19. The apparatusof claim 18, in which the hysteresis circuit is integrated with themicroprocessor.
 20. The apparatus of claim 18, further comprising ananalog-to-digital converter coupled to the integrator and to themicroprocessor, in which the microprocessor is further configured toobtain the electron count from the integrator as a digital value fromthe analog-to-digital converter, in which the analog-to-digitalconverter is integrated with the microprocessor.